Using stable isotopes to quantify ecohydrological flux dynamics at the soil-plant-atmosphere continuum in urban green spaces

2020 ◽  
Author(s):  
Lena-Marie Kuhlemann ◽  
Doerthe Tetzlaff ◽  
Birgit Kleinschmit ◽  
Stenka Vulova ◽  
Chris Soulsby
Keyword(s):  
Stable Isotopes ◽  
Soil Moisture ◽  
Groundwater Recharge ◽  
Green Spaces ◽  
Convective Precipitation ◽  
Urban Water ◽  
Water Fluxes ◽  
Urban Green ◽  
Urban Green Spaces ◽  
Water Partitioning

<p>Urban areas, more than many experimental catchments, are characterized by a markedly heterogeneous distribution of land covers, with different degrees of permeability that radically vary partitioning of precipitation into evapotranspiration (“green” water fluxes) and runoff and groundwater recharge (“blue” water fluxes). While the quantification of ecohydrological fluxes using stable isotopes in water as environmental tracers has been an established method for many years, surprisingly few studies have been applied to the highly complex urban water cycle. To determine the effects of representative urban green space “types” on water partitioning, we carried out plot-scale studies at a heterogenous field site in Berlin-Steglitz that integrates climate, soil moisture and sap flow data, with isotope sampling of precipitation and soil moisture on a regular basis. Soil moisture and isotope measurements were conducted at different depths and under contrasting soil-vegetation units (grassland, trees, shrub) with different degrees of permeability. Our investigations revealed uniformly decreasing soil moisture content during the dry summer of 2019, with only temporary re-wetting of the uppermost soil layers despite heavy convective precipitation events. Soils under trees were driest, whilst grassland soils were wettest, with shrubs intermediate. Isotope-based modelling indicated that this was the result, of greater interception, transpiration and – surprisingly – soil evaporation from forest sites. The isotope signatures of soil water also revealed stronger “memory effects” of summer drying in forest soils, which persisted until the major re-wetting of the system in autumn allowed drainage from the soil profile to contribute to groundwater recharge. Modelling showed that recharge under grasslands could be over 3 times higher compared to under trees and shrubs. Upscaling these findings with large-scale isotope studies of surface and groundwater across Berlin highlights the importance of the vegetation in urban green spaces to water partitioning in heterogeneous city landscapes and the need for careful integration of vegetation management in urban water and land use planning.</p>

Quantifying the effects of urban vegetation on water partitioning in complex cityscapes: the potential of isotope-based ecohydrological models

2020 ◽  
Author(s):  
Mikael Gillefalk ◽  
Dörthe Tetzlaff ◽  
Reinhard Hinkelmann ◽  
Lena-Marie Kuhlemann ◽  
Aaron Smith ◽  
...  
Keyword(s):  
Urban Heat Island ◽  
Groundwater Recharge ◽  
Water Use ◽  
Green Spaces ◽  
Heat Island ◽  
Urban Green ◽  
Urban Green Spaces ◽  
Island Effect ◽  
Water Partitioning ◽  
Urban Heat

<p>The continued global acceleration of urbanisation increasingly requires sustainable, adaptive management strategies for land and water use in cities. Although the effects of buildings and sealed surfaces on urban runoff generation (via storm drains) and local climate (through the urban heat island effect) are well known, much less is known about how these artificial influences integrate with water partitioning in more natural urban green spaces. In particular, little is quantitatively known about how different types of urban green spaces (lawns, parks, woodland etc.) regulate the partitioning of evaporation, transpiration and groundwater recharge. To address this crucial issue, we integrated field observations with advanced, isotope-based ecohydrological modelling at the plot scale in the urban area of Berlin, Germany. Measurements of soil moisture, sap flow, and stable isotopes in precipitation, soil water and groundwater have been made over the course of one growing season. Additionally, an eddy flux tower at the site Rothenburgstraße in Berlin-Steglitz continuously collects hydroclimate data by measuring temperature, precipitation, radiation, humidity and wind speed at high temporal resolution. These data (30-min averages) have been used as input to, and for calibration of, the process-based ecohydrological model EcH<sub>2</sub>O-iso. The model also tracks stable isotope ratios and water ages in various stores (e.g. soils and groundwater) and fluxes (evaporation, transpiration and recharge). EcH<sub>2</sub>O-iso has successfully been used to describe the effects of vegetation cover on water partitioning in a number of studies but this is the first implementation in an urban setting. It shows that ecohydrological water use by vegetation type increases in the order forests > shrubs > grass, mainly through higher interception and transpiration. Accordingly, trees can reduce groundwater recharge by >50%, but provide cooling latent heat transfers to the atmosphere.  Similarly, ages of stored water and fluxes are generally greater under trees than grass. The results, which form the basis for future upscaling, show that urban green spaces play an important role in urban hydrology and in Berlin there is a trade-off between moderating the urban heat island effect and maintaining groundwater recharge. Consequently, it is clear that vegetation management needs to be considered in sustainable water and land use planning in urban areas to build resilience in cities to climatic and other environmental change.</p>

scholarly journals Quantifying the effects of urban green space on water partitioning and ages using an isotope-based ecohydrological model

2021 ◽  
Author(s):  
Mikael Gillefalk ◽  
Dörthe Tetzlaff ◽  
Reinhard Hinkelmann ◽  
Lena-Marie Kuhlemann ◽  
Aaron Smith ◽  
...  
Keyword(s):  
Groundwater Recharge ◽  
Green Space ◽  
Urban Green Space ◽  
Green Spaces ◽  
Green Water ◽  
Runoff Generation ◽  
Urban Green ◽  
Urban Green Spaces ◽  
Water Partitioning ◽  
Ecohydrological Model

Abstract. The acceleration of urbanisation requires sustainable, adaptive management strategies for land and water use in cities. Although the effects of buildings and sealed surfaces on urban runoff generation and local climate are well known, much less is known about the role of water partitioning in urban green spaces. In particular, little is quantitatively known about how different vegetation types of urban green spaces (lawns, parks, woodland etc.) regulate partitioning of precipitation into evaporation, transpiration and groundwater recharge; and how this partitioning is affected by sealed surfaces. Here, we integrated field observations with advanced, isotope-based ecohydrological modelling at a plot scale site in Berlin, Germany. Soil moisture, sap flow, together with stable isotopes in precipitation, soil water and groundwater recharge, were measured over the course of one growing season under three generic types of urban green space: trees, shrub and grass. Additionally, an eddy flux tower at the site continuously collected hydroclimate data. These data have been used as input and for calibration of the process-based ecohydrological model EcH2O-iso. The model tracks stable isotope ratios and water ages in various stores (e.g. soils and groundwater) and fluxes (evaporation, transpiration and recharge). Green water fluxes in evapotranspiration increased in the order shrub (381 ± 1 mm) 

scholarly journals Quantifying the effects of urban green space on water partitioning and ages using an isotope-based ecohydrological model

2021 ◽  
Vol 25 (6) ◽  
pp. 3635-3652
Author(s):  
Mikael Gillefalk ◽  
Dörthe Tetzlaff ◽  
Reinhard Hinkelmann ◽  
Lena-Marie Kuhlemann ◽  
Aaron Smith ◽  
...  
Keyword(s):  
Groundwater Recharge ◽  
Green Space ◽  
Growing Season ◽  
Urban Green Space ◽  
Green Spaces ◽  
Green Water ◽  
Urban Green ◽  
Urban Green Spaces ◽  
Water Partitioning ◽  
Ecohydrological Model

Abstract. The acceleration of urbanization requires sustainable, adaptive management strategies for land and water use in cities. Although the effects of buildings and sealed surfaces on urban runoff generation and local climate are well known, much less is known about the role of water partitioning in urban green spaces. In particular, little is quantitatively known about how different vegetation types of urban green spaces (lawns, parks, woodland, etc.) regulate partitioning of precipitation into evaporation, transpiration and groundwater recharge and how this partitioning is affected by sealed surfaces. Here, we integrated field observations with advanced, isotope-based ecohydrological modelling at a plot-scale site in Berlin, Germany. Soil moisture and sap flow, together with stable isotopes in precipitation, soil water and groundwater recharge, were measured over the course of one growing season under three generic types of urban green space: trees, shrub and grass. Additionally, an eddy flux tower at the site continuously collected hydroclimate data. These data have been used as input and for calibration of the process-based ecohydrological model EcH2O-iso. The model tracks stable isotope ratios and water ages in various stores (e.g. soils and groundwater) and fluxes (evaporation, transpiration and recharge). Green water fluxes in evapotranspiration increased in the order shrub (381±1mm)<grass(434±21mm)<trees(489±30 mm), mainly driven by higher interception and transpiration. Similarly, ages of stored water and fluxes were generally older under trees than shrub or grass. The model also showed how the interface between sealed surfaces and green space creates edge effects in the form of “infiltration hotspots”. These can both enhance evapotranspiration and increase groundwater recharge. For example, in our model, transpiration from trees increased by ∼ 50 % when run-on from an adjacent sealed surface was present and led to groundwater recharge even during the growing season, which was not the case under trees without run-on. The results form an important basis for future upscaling studies by showing that vegetation management needs to be considered within sustainable water and land use planning in urban areas to build resilience in cities to climatic and other environmental change.

scholarly journals Effects of organic ground covers on soil moisture content of urban green spaces in semi-humid areas of China

2021 ◽  
Vol 60 (1) ◽  
pp. 251-259
Author(s):  
Yichuan Zhang ◽  
Lifang Qiao ◽  
Chaoping Chen ◽  
Li Tian ◽  
Xiaozhen Zheng
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Soil Moisture Content ◽  
Green Spaces ◽  
Urban Green ◽  
Urban Green Spaces

scholarly journals Using soil water isotopes to infer the influence of contrasting urban green space on ecohydrological partitioning

2021 ◽  
Vol 25 (2) ◽  
pp. 927-943
Author(s):  
Lena-Marie Kuhlemann ◽  
Doerthe Tetzlaff ◽  
Aaron Smith ◽  
Birgit Kleinschmit ◽  
Chris Soulsby
Keyword(s):  
Soil Water ◽  
Green Space ◽  
Urban Green Space ◽  
Green Spaces ◽  
Urban Vegetation ◽  
Urban Water ◽  
Isotopic Tracers ◽  
Urban Green ◽  
Urban Green Spaces ◽  
Prolonged Drought

Abstract. In cities around the world, urban green spaces provide a range of benefits and ecosystem services. However, recent years have shown how prolonged warm and dry periods can affect urban water resources and lead to water stress in vegetation in urban green spaces, even in temperate regions. Consequently, quantitative knowledge about ecohydrological partitioning in different types of urban green space is crucial for balancing sustainable water needs in cities during future challenges of increasing urbanization and climate warming. Using isotopic tracers in precipitation and soil water, along with conventional hydrometric measurements in a plot-scale study in Berlin, Germany, we investigated water partitioning under different generic types of urban vegetation (grassland, shrub and trees). This allowed for the assessment of urban vegetation effects on evapotranspiration, subsurface flow paths and storage during a prolonged drought period with episodic rainfall. Despite higher soil evaporation losses under urban grassland, higher interception and transpiration likely contributed to slower turnover of soil water and older groundwater recharge under urban trees. Shrub vegetation seemed to be most resilient to prolonged drought periods, with lower evapotranspiration losses. Our results contribute to a better understanding of ecohydrological partitioning under mixed urban vegetation communities and an evidence base for better adaptive management of urban water and irrigation strategies to sustainably meet the water demands of urban green spaces in the future.

scholarly journals A distributed soil moisture, temperature and infiltrometer dataset for permeable pavements and green spaces

2020 ◽  
Vol 12 (1) ◽  
pp. 501-517
Author(s):  
Axel Schaffitel ◽  
Tobias Schuetz ◽  
Markus Weiler
Keyword(s):  
Time Series ◽  
Soil Moisture ◽  
Green Spaces ◽  
Data Repository ◽  
High Temporal Resolution ◽  
Urban Water ◽  
Energy Fluxes ◽  
Infiltration Capacity ◽  
Urban Green Spaces ◽  
Permeable Pavements

Abstract. Knowledge of water and energy fluxes is key for urban planning and design. Nevertheless, hydrological data from urban environments are sparse, and, as a result, many processes are still poorly understood and thus inadequately represented within models. We contribute to reducing this shortfall by providing a dataset that includes time series of soil moisture and soil temperature measured underneath 18 different permeable pavements (PPs) and 4 urban green spaces located within the city of Freiburg (Germany). Time series were recorded with a high temporal resolution of 10 min using a total of 65 individual soil moisture sensors and covering a measurement period of 2 years (November 2016–October 2018). The recorded time series contain valuable information on the soil hydrological behavior of PPs and demonstrate the effect of surface properties and surrounding urban structures on soil temperatures. In addition, we performed double-ring infiltration experiments, which in combination with the soil moisture measurements yielded soil hydrological parameters for the PPs, including porosity, field capacity and infiltration capacity. We present this unique dataset, which is a valuable source of information for studying urban water and energy cycles. We encourage its usage in various ways, e.g., for model calibration and validation purposes, study of thermal regimes of cities, and derivation of urban water and energy fluxes. The dataset is freely available from the FreiDok plus data repository at https://freidok.uni-freiburg.de/data/151573 and https://doi.org/10.6094/UNIFR/151573 (Schaffitel et al., 2019).

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